1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method thereof.
2. Description of the Related Art
In recent years, the technique for manufacturing a semiconductor device such as a thin film transistor (hereinafter referred to as a TFT) over a substrate has advanced drastically, and has been developed to be applied to an active-matrix display device for example. In particular, a TFT using a crystalline semiconductor film can operate at high speed since the TFT has higher field-effect mobility (also referred to as mobility) than a TFT using a conventional amorphous semiconductor film.
As an example of forming a TFT over a substrate, there is one in which a base film, an active layer, a gate insulating film, a gate electrode, an interlayer insulating film, and a source or drain electrode are formed in this order. In order to further increase response speed of this TFT, decreasing contact resistance with the source or drain electrode by forming silicide in a source or drain region of the active layer can be considered other than shrinking a design rule.
In order to form such silicide, titanium (Ti), nickel (Ni), cobalt (Co), tungsten (W), platinum (Pt), or the like is generally used (refer to patent document 1: Japanese Published Patent Application No. H10-98199).